Telephone or like system



June 4- D. A. CHRISTIAN ET AL 3 5 I TELEPHONE OR LIKE SYSTEM 7 I -F iled Sept. B, 1941 2 SheetLs-Sheet 1 /v/vra@" any/0 mm was mm Z Viv/0 mgsroko a?) ATTORWE June 6, 19 D. A. CHRISTIAN ETAL TELEPHONE 0B LIKE SYSTEM Filed Sept. 18, 1941. 2 Sheet s-Sheet 2 M v, mma E N. NNR R Elm 0 W w. Jmw, A HMM W Patented June 6, 1944 TELEPHONE 0R LIKE SYSTEM I David Adam Christian and David Langsford Clay,

London, England, assignors to Siemens Brothers & Co. Limited, Westminster, London, England, a British company Application September 18, 1941, Serial No. 411,288

In Great Britain November 1, 1940 14 Claims. (01'. ma-1c) The presentinvention relates to automatic telepho'ne'and like selective systems, and has in view theprovision of improved arrangements for the reception of direct current impulses in such systems. It is especially applicable to'the case in which a feeding-bridge circuit has to provide for the reception of direct current impulses.

The improvement aimed at in the impulsereceiving arrangements according to the'invention is an increasedspeed of response of the arrangements to a pertinent change of condition of the controlling circuit.

In practice, quick response of an electromagnetic impulse-receiving relay is especially difiicult to obtain when the circuit controlling it is a transmission line having relatively high capacity between the conductors or between the conductors and earth. In the impulse-receiving arrange'ments according "to the invention, the improvement just referred to is achieved either by the provision of arrangements which act to increase the speed at which an impulse-receiving relay responds to a pertinent change of condition of the controlling circuit, or by causing an action which the response of an impulse-receiving relay is required to effect to be initiated prior to such response by an auxiliary relay which r..- spondsearlier to the pertinentchange of condition of the controlling circuit.

. According to one main feature of the invention, arrangements for-the reception of direct current. impulses are such that when the condition existing in the controlling circuit is the make condition, a circuit is. completed via the controlling circuit for energising windings on an .2.

electromagnetic -.impulse-receiving relay and a further inductive element, and that when the conditionof the controlling circuit is. changedfromone particular one of thetwo impulsing. conditions to the other (e. g. from the make con.- dition to the breakj. condition) the resulting change of flux in the said inductive element results in thegeneration in a winding on the-element of a voltage impulse which is utilisedto increasethe speed at which the arrangements effectively respond .to the said change of condition.

According to another main feature of the invention arrangements for the reception of direct current impulses are such that when the condition. existing on the controlling circuit is the make condition, a circuit is completed via the controlling circuit for energising windings on an electromagnetic impulse-receiving relay and a further inductive element, and that when the condition of the controlling circuit is changed from either of the two impulsing conditions to the other, the resultingchange of flux in the said inductive element results in the generation in'a winding on the element of a voltage impulse which is utilised to increase the speed at which the arrangement-effectively responds to the said change of condition.

In the case where the impulse-receiving arrangements are situated at a feeding-bridge of the type employing a so-called repeating coil, the further inductive element may conveniently be this coil which may for the purpose of carrying out the invention have a winding additional to the windings usually provided. The voltage impulse referred to may be utilised by arranging that-it produces a current impulse in a winding on the impulse-receiving relay, or by arranging that it momentarily operates a high-speed auxiliary relay which brings about the increase in speed of the response to the change of condition.

Instead of using a winding of the repeating coil as the further inductive element, a separate inductance coil may be used and this may be so connected and related to the windings of the impulse receiving relay that the desired current impulse in a winding of the impulse receiving relay is produced. Arrangements of this kind can also be employed in cases where the impulse receiving relay is connected in a feeding bridge of the Stone type.

In an arrangement using a high'speed relay this relay may be connected to a. third winding on the impulse receiving relay itself.

In the arrangements referred to. above and which do not include the. high speed auxiliary relay, it may be necessary to employ a polarised impulse receiving relay as with an ordinary nonpolarised relay the danger exists that the momentary currents referred to may produce in the relay a reversed flux large enough to eifect momentary re-operation of. the relay. In the cases Where it is possible-to. employ. a nonpolarisedrelay some of the arrangements referred to will also tend to increase the speed, of operation of the impulse receiving relay.

It should be noted that in cases where a relay winding provided for the purpose of the invention isliable to have speech currents produced in it, precautions must betaken to ensure that the current surge normally produced in the winding to assist therelay to change its state. or to effect momentary operation of the relay is substantially greater than any surge due to speech.

Several embodiments of the invention applied to an automatic telephone system will now be described by way of example with reference to the accompanying drawings. Figs. 1 to 3 show applications of the invention to a feeding-bridge in which the incoming and outgoing lines are coupled by a repeating coil and Figs. 5 to 7 show application of the invention to a feeding bridge of the Stone type. Figs. 4 and 8 are circuit diagrams applicablein general to the arrangements of Figs. 1 to 3, and Figs. 5 to '7 respectively.

In the figures the windings of the impulse re- In Fig. 1 similar inductance coils IC are connected in shunt to the windings of the impulse receiving relay A, the parallel connected windings being connected in the feed circuit between the exchange battery and the repeating coil RC. The inductance coils 10 have such characteristics and the windings are so connected that when the condition of the incoming circuit is changed from the make condition to the break condition, the decay of the flux in the coils generates in the windings of th relay A an impulse the voltage of which is greater than that produced at the time in the relay winding itself. These two voltages are in opposition, that due to the decay of flux in the relay winding producing a current tending to delay release of the relay whilst that due to the decay of the flux in the inductance coil produces a current tending to reverse the flux in the relay and hastens its release, the result being a hastening of the release of the impulse receiving relay.

In the arrangement shown in Fig. 2 the impulse receiving relay A is connected to the repeating coil RC in the usual manner. The relay is provided with an additional winding (III) connected in a closed circuit with an additional windin (III) on the repeating c0il.. It. is arranged that when the condition of the incoming circuit changes from the make condition to the break? condition, the decay of the flux in the repeating coil generatesav'oltag in its additional winding (III) which is such as to produce a momentary current in the additional winding of relay A and in such a direction that it tends to reverse the flux in that relay and so hasten its release.

In this arrangement and in the arrangement shown in Fig. 1, it may be necessary to use a polarised impulse receiving relay as with an ordinary relay the danger exists that the reversal of flux du to the dissipation of the energy of the inductance coil may bring about the momentary operation of the relay. In cases where the use of a non-polarised relay is permissible the'arrangemen'ts will also tend to increase the speed of operation of the relay.

A somewhat similar arrangement may be employed in which similar windings of an inductance coil are connected in series with the impulse receiving relay, a third winding. of the inductance coil and a third winding of the relay being connected .in a closed circuit in a similar manner to that shown for the windings (III) of Fig, 2 and arranged to produce alike efiect.

Another. arrangement that may be employed is shown in Fig. 3." In this arrangement an additional relay, which may be of the high speed low inductance type, and which is here designated X is connected to an additional winding (III) of the repeating coil RC, a rectifier MR being connected in the closed circuit in such a sense that the relay X is only operated when the condition of the incoming circuit changes from th "make" condition to the break condition. Contacts of this relay when operated disconnect the windings of relay A from the line windings of the repeating coil RC and connect the latter to non-inductive resistances NIR through which the energy in the repeatin coil may be dissipated. For this purpose the change over contacts should be of the make-before-break type.

In a modification of the arrangements shown in Fig. 3 the non-inductive resistance and the change over contacts of relay X may be omitted and a break contact of relay X may be connected in the outgoing line circuit. Relay X is only operated momentarily but it will open its contact in the line circuit thus terminating the "make condition before relay A releases although the release of the latter has been hastened consequent on the voltage set up across winding (III) of the coil RC.

Fig. 4 shows the circuit arrangements governing the repetition of impulses by the method of Figs. 1 to 3 and the modifications described. With regard to Figs. 1 and 2 and the modification of the latter it is to be understood that contact 0: is not present and that earth is connected directly to contact a. In Fig. 4 relay AA is the impulse repeating relay having contact aa connected in the outgoing line circuit, relay B is the usual slow releasing release relay and relay C is the slow releasing so-called dialling relay, the function of which is to determine the end of an impulse train by its release. When it is operated, relay C closes a low impedance loop across the outgoing impulsing circuit in the usual manner. When the circuit containing the impulse repeater is taken into use, relay A operates in known manner over a preceding loop and at its contact a closes circuits for relays AA and B. A metal rectifier MRI is connected in the circuit of relay AA to guard against operation of. that relay by an inductive kick when contact (2 opens. Relays AA and B operate and contact ca closes the forward impulsing loop. When the first impulse break occurs, relay A releases, releasing relay AA to repeat the break over the outgoing circuit and operating relay C. At the endof the "break period when the make condition is again imposed relays A and AA re-operate. Relay 0 remains operated throughout the impulse train and is released at the end of the train consequent on the continued operation of relay A. Relay B remains held during impulsing and until the connection is terminated by the final release of relay A. When the arrangements are applied to Fig. 3, operation of relay A brings about the operation of relays 1AA and B as before. At the beginning of the impulse when the make" condition changes to a break condition relay X operates, initiating the release of relay AA and the operation of relay C at its contact :0 Contacts :0 and :0

' change over, disconnecting relay A and connecting the repeating coil RC to the non-inductive resistances NIR for th purpose previously described. Relay A releases before relay X due to the combined effect of the third winding of the repeating coil on the relay and the disconnection of the relay from the line so that relay AA is not re-operated until the condition of the incoming circuit again reverts to the make condition.

When the arrangements are applied to the modification of Fig. 3 above described, operation of relay X besides efiecting. the release ofrelay AA andoperation of" relay C opens the outgoing loop thereby guarding against'any release lag of relay A and anticipating the release of relay AA which takes place shortly after. Release of relay A ishastened by the effect of the third winding of the repeating coil on the relay .circuit and the relay releases before relay X.

Figs; 5 and '7 show'how the arrangements of Figsrl and 3 may be appliedto a Stone; bridge and 'Fig. 6 shows a similar adaptation of the arrangement described as a modification of Fig. 2. Fig. '7 may be modified in a manner to correspond to the modification described of Fig. 3. In a further modification of Fig; '7, the high speed relay and rectifier may be connected with an additional winding on the impulse receiving relay itself. Fig. 8 shows the circuit arrangements governing impulse repetition. It is thought that no further description of these figures is necessary as the method of operation will be clear to those skilled in the art from a consideration of the methods governing the operationof Figs. 1 to 4 which have been fully described. In the arrangements shown in Figs. 5 and 6 the use of a polarised relay may be necessary.

In all the figures it is to be understood that the circuits shown are only those necessary for the understanding of the invention. Contacts of relays B, C and D have been omitted as well as contacts which would normally be included in the circuit for relay in Figs. 4 and as the connections "of these and their use are well known.

What we claim as new and desire to secure by Letters Patent is:

lJAn impulse repeating circuit comprising an incoming impulsing circuit and an outgoing impulsing circuit, a two winding impulse receiving relay in said incoming circuit, means controlled by said relay for repeating impulses, received by said relay, over said outgoing circuit, a pair of inductances, one of said inductances connected in parallel with one winding of said impulse receiving relay and the other of said inductances' connected in parallel with the oeer winding of said impulse receiving relay whereby when the condition of the incoming circuit is changed from a condition for energizing said relay and said inductances to a condition for deenergizing said relay and inductances a voltage impulse is generated in the windings of said inductances to cause the magnetic flux in said relay to rapidly decay.

2. In an impulse repeating circuit arrangement, an incoming circuit, an outgoing circuit, receiving means controllable over said incoming circuit to respond to impulses transmitted thereover, a transmitting relay controllable by said receiving means to transmit impulses over said outgoing circuit, and inductive means effective upon the termination of each impulse transmitted over said incoming circuit to said receiving means to generate a voltage impulse, said transmitting relay deenergized independently of said receiving means responsive to said voltage impulse thereby to terminate each impulse transmitted over said outgoing circuit, whereby the termination of each impulse transmitted over said outgoing circuit is substantially commensurate with the termination of each impulse received over said incoming circuit.

3. In an impulsing circuit arrangement, an impulse receiving relay, a circuit over which impulses are transmitted to said relay, said relay energized at the beginning of each impulse trans mitted over said circuit and maintained energized over said circuit until said impulse is terminated, and inductive means coupled to said circuit eiIective responsive to the termination of eachimpulse transmitted over said circuit to generate a voltage impulse in such a direction in said relay that the time required to restore the relay to normal after the termination of each impulse is less than'the time which would be required to restore the relay to normal if the inductive means were not coupled to said circuit.

4. An impulse circuit comprising an incoming impulsing circuit, an impulse receiving relay, a Winding on said relay connected in said circuit, and an inductive element connected in another circuit across the winding of said relay effective responsive to a change in said circuit from one of two impulsing conditions to another to generate a voltage impulse in said circuit whereby the normal speed of response of said relay is increased.

5. An impulsing circuit comprising an incoming impulsing circuit, a two-winding impulse receiving relay in said circuit, and an inductive element shunting each winding of said relay effective response to a change in said circuit'from a make impulsing condition to a break impulsing condition to generate a voltage impulse in each of the windings of said relay whereby normal speed of release of said relay is increased.

6. An impulsing circuit comprising an incoming impulsing circuit, a two-winding impulse receiving relay in said circuit, and an inductive element shunting each of the windings of said relay efiective responsive to a change in said circuit from a condition of energization of said relay to a condition of deenergization of said relay to generate a voltage impulse in said circuit whereby the normal rate of decay of magnetic flux in said relay is increased.

7. An impulsing circuit comprising an incoming impulsing circuit, an impulse receiving relay in said circuit, and a voltage generating device connected in parallel with said impulse receiving relay in said circuit and effective responsive to a change in said circuit from one of two impulsing conditions to another to generate a voltage impulse in said relay whereby the normal speed of deenergization of said relay is increased.

8. In an impulsing circuit, an impulse receiving relay, a pair of incoming conductors connected to said relay over which impulses are transmitted to said relay, and a voltage generating device connected to said conductors in arallel with said relay in said circuit, said voltage generating device effective responsive to the termination of an impulse to said relay for generating a voltage impulse in said parallel circuit, said voltage impulse effecting the rate at which the magnetic flux in said relay decays responsive to the termination of an impulse to said relay to thereby cause the relay to more rapidly restore to normal.

9. In an impulsing circuit arrangement, an impulse receiving relay, a circuit over which impulses are transmitted to said relay, said relay energized at the beginning of each impulse transmitted over said circuit, and an inductive element coupled to said circuit efiective responsive to the termination of each impulse transmitted over said circuit to generate a voltage impulse, and means controlled by said voltage impulse for disconnecting said relay from said circuit.

10. An impulse repeating circuit comprising an incoming impulsing circuit and an outgoing impulsing circuit, a repeating coil inductively coupling said incoming circuit and said outgoing circuit, an impulse receiving relay in said incomingcircuit, means controlled by said relay for repeating impulses received thereby over said outgoing circuit, and an inductive element shortcircuiting said relay effective responsive to a changein said incoming circuit from a condition energizing said relay to a condition deenergizing said relay to generate a voltage impulse in said inductive element in such a direction that the speed at which the flux in said relay decays, responsive to the removal of the energized condition of said relay, is increased to thereby increase the speed of restoration of said relay.-

11'. An impulse repeating circuit comprising an incoming impulsing circuit and an outgoing impulsing circuitga two-winding impulse receiving relay, arepeating coil, a circuit for energizing said relay including a winding of said repeating coil and said incoming impulsing circuit, means controlled responsive to the energization of said relay for closing said outgoing impulsing circuit including another winding of said repeating coil, an inductance having a pair of windings each of which is connected in a parallel circuit with each winding of said impulse receiving relay, said inductances effective, responsive to the break of the incoming circuit, to generate a voltage impulse in such a direction inthe windings of said impulse receiving relay that the speed of deenergization of said relay to thereby control said outgoing impulsing means to open the said outgoing impulsing circuit is increased.

- 12. An impulse repeating circuit comprising an incoming receiving circuit and an outgoing impulsing circuit, a repeating coil for inductively coupling said circuits, a three-winding impulse receiving relay, one winding of said relay connected to said incoming impulsing circuit by way of one winding of said repeating coil and the second winding of said relay connected to said incoming impulsing circuit by way of another winding of said repeating coil, an inductive element inductively coupled to said repeating coil and connected in a local circuit with the third winding on said impulse receiving relay, said inductive element effective responsive to a change in said incoming circuit from one of two impulsing conditions to the other to generate a voltage creased.

impulse in said local circuit whereby a normal speedof deenergization of said relay responsive to the change in said impulsing condition is in- 13. In an impulse repeating circuit, a control circuit, an impulse repeating relay connected in said control circuit, said control circuit adapted to be closed and opened to energize and deenergize said relay, an outgoing impulsing circuit, means controlled responsive to the energization of said relay for closing said outgoing impulse circuit during the time that said relay is maintained energized oversaid control circuit, another circuit shunting said relay, and means in said other circuit effective responsive to the opening of said control circuit for generating a voltage impulse in said shunting circuit which is in opposition to, and of greater strength than, the voltage impulse generated in said relay responsive to the decay of flux therein upon the opening of said control circuit, said voltage impulse generated by said means in said shunting circuit being of sufiicient strength to overcome the flux in said relay to thereby increase the speed of release thereof. s

14. In an impulse repeating circuit arrangement, an impulse receiving relay having a pair of windings, an incoming circuit for controlling said relay including both windings thereof, said relay energized responsive to the closure of said incoming circuit and deenergized responsive to the opening of said incoming circuit, said incoming circuit having a normal impedance such that said relay has a tendency to remain in its energized position for a substantial period of time after said incoming circuit therefor is opened, an outgoing circuit, means controlled responsive to the energization of said relay for closing said outgoing circuit, and inductive means controlled over said incoming circuit, responsive to the opening of said incoming circuit for generating a voltage impulse, said voltage impulse overcoming the tendency of the impedance to maintain said 

